1. Field of the Invention
The present invention relates to a liquid discharge head that discharges a liquid such as ink to perform a recording operation, and a method for manufacturing the same.
2. Description of the Related Art
The liquid discharge head includes an external signal input terminal electrically connected to a recording apparatus body side to receive, from a recording apparatus body, an electric signal or power used for driving an energy generation element that generates energy used for discharging a liquid. To connect the external signal input terminal to a recording element substrate that includes the energy generation element, an electric wiring member including a flexible tape member is generally used. The electric wiring member, which is configured by sandwiching copper foil between base film and cover resin film and bonding and stacking each member, has a device hole that is an opening for installing the recording element substrate. Wiring of the electric wiring member including the copper foil can be classified into power lines and signal lines for driving the energy generation element. The power lines include a wiring for applying a driving voltage and a ground wiring of the driving voltage. The electric wiring member and the recording element substrate are electrically interconnected by bonding together an inner lead exposed from the electric wiring member to the device hole and an electric connection unit disposed in the recording element substrate.
Japanese Patent Application Laid-Open No. 2006-297753 discusses a method for achieving electric connection with connection strength suppressed for variance by setting almost equal the sums of areas of connected portions of the inner lead and the terminal when the inner lead and the electric connection unit are interconnected by a gang bonding method.
In the electric connection between the electric connection unit of the recording element substrate and the inner lead of the electric wiring member, to reduce wiring resistance of the electric wiring member, a wiring width of the electric wiring member can be set large. To reduce the wiring resistance, there is known a method for setting a base of the inner lead larger than a leading end of the inner lead exposed to the device hole of the electric wiring member. However, the large width of the base of the inner lead causes an increase in inner lead's own reaction, creating a possibility that failures will occur during bonding.
To reduce wiring resistance of a wiring tape and achieve good bonding, there is a method for reducing a width of the wiring in a portion in which no wiring of the electric wiring member is exposed to the device hole, namely, a region sandwiched between the base film and the cover film.
However, with miniaturization of the recording element substrate, a higher density of the wirings, and an increase in number of energy generation element, a current amount applied to each power line for driving the energy generation element tends to increase. Electric resistance then increases in a portion in which a width of the inner lead of the electric wiring member is small, causing heat to easily accumulate. Furthermore, the portion of the thin wiring in which heat easily accumulates is filled with heat more easily when it is sandwiched between the films which constitute the electric wiring member.